In a ground-state rhodium atom, the subshell is partially filled. In a ground-state rhodium atom, the subshell is partially filled. 4p 5s 5p 3d 4s

The 5s subshell is partially filled in the ground-state rhodium atom

Explanation:

The filling up of electrons in the atom of an element follows the Aufbau principle.

Aufbau principle states that electrons fill electron shells around atoms according to the energy level with those of lower energy levels filled first. This means that electron shells and subshells around atoms start filling up with electrons first since their energy levels progressively increases, except in some cases where an outer shell has a low energy level and partly fills up before an inner shell is full.

These exceptions are based on the fact that half-full or full shells or subshells are more stable than partially filled ones. When there is small or negligible difference in energy levels between two subshells, an electron may move to the higher level shell to fill or half-fill it thereby conferring stability to the atom. These exceptions are common in elements with higher atomic number as the differences in energy levels become smaller. An example is the rhodium atom.

Rhodium atoms have 45 electrons and the shell structure is  2,8,18,16,1.  The ground state electron configuration of ground state gaseous neutral rhodium atom is [Kr],4d85s1. The inner 4d and the outermost 5s subshells are partially filled.

i just learnt this recently but i need to look through my notes again

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.